RU2731174C1 - Method of producing high-processed pulp - Google Patents

Abstract

FIELD: pulp and paper industry.

SUBSTANCE: invention relates to pulp and paper industry and is intended for production of high-processed pulp from non-wood vegetal raw material used in production of cellulose ethers. Method of producing high-processed pulp involves delignification of ground vegetable material by boiling raw material in a hydrogen peroxide solution in the presence of sulfuric acid and a catalyst, in form of molybdic acid salts and bleaching, non-wood vegetal raw material is taken as vegetable raw material, and the stages of catalytic delignification and bleaching are carried out with continuous thermomechanochemical activation by passing the reaction mass of plant raw material through the outer contours of the delignification and bleaching tanks, equipped with an ultrasonic device or device of rotating anisotropic ferromagnetic bodies for 60–90 minutes, wherein delignification solution contains sulfuric acid 0.6 wt%, hydrogen peroxide 2 wt% and molybdate sodium catalyst 0.2 wt%, and bleaching is carried out after delignification in peroxide-alkaline solution containing 6 wt% sodium hydroxide and hydrogen peroxide with initial concentration of 8 wt% at temperature 90–95 °C.

EFFECT: technical result is obtaining of high-processed pulp from non-wood vegetal raw material with content of α-cellulose up to 97_9 % and content of residual lignin to 0_25 %, increased yield of the ready product in a shorter period of time.

1 cl, 3 dwg, 1 tbl

Description

The invention relates to the pulp and paper industry and is intended to produce highly refined cellulose from non-woody plant raw materials used in the production of cellulose ethers.

A known method for producing cellulose (options):

The method for producing cellulose according to the first option is carried out with simultaneous loosening and cleaning of cellulose-containing material, cooking in an alkaline solution, washing, bleaching, washing, drying, in which, after simultaneous loosening and cleaning, grinding, soaking in NaOH solution and cleaning is carried out, cooking is carried out in an alkali solution for 1.5-3 hours with a hydromodule 1: (5-20), containing an additional surfactant, bleaching is carried out in a solution of H ₂ O ₂ , and before drying, spinning is carried out.

The preferred embodiment is when acid is carried out after bleaching in an acid solution; when grinding is carried out before drying.

The method for producing cellulose according to the second embodiment is carried out with simultaneous loosening and purification of cellulose-containing material, cooking in an alkaline solution, washing, bleaching, washing, drying, in which cooking is carried out in an alkaline solution, additionally containing a surfactant, for 1.5-3 hours at a hydromodule 1: (5-20), bleaching is carried out in a solution of H ₂ O ₂ for 1-2 hours at a hydromodule 1: (5-20), and before drying, spinning is carried out.

The preferred embodiment is when acid is carried out after bleaching with an acid solution; before drying, the material is crushed, see. RU Patent No. 2304647, IPC D21C 5/00 (2006.01), D21C 1/06 (2006.01), D21C 3/02 (2006.01), D01C 1/02 (2006.01), 2007.

The disadvantage of the known variants of the method is the duration of the process.

A known method of producing cellulose by cooking cellulose-containing raw materials with the addition of anthraquinone production waste as a catalyst, obtained by catalytic vapor-phase oxidation of anthracene, in which the production waste of anthraquinone is treated in an ultrasonic field in a mixture with white liquor with a mass ratio of white liquor: anthraquinone production waste 5 ÷ 1: 1 or black liquor with a mass ratio of black liquor: anthraquinone production waste 1 + 4: 1.

The preferred implementation of the method, when the processing of waste production of anthraquinone in an ultrasonic field is carried out for 3-10 minutes, see RU No. 2287035, IPC D21C 3/02 (2006.01), 2006.

The disadvantage of this method is the high content of residual lignin in the target product.

The closest in technical essence is a method of obtaining highly refined cellulose, including aqueous or acidic prehydrolysis of crushed plant raw materials, after prehydrolysis, delignification of wood residue is carried out by cooking raw materials in a solution of hydrogen peroxide in the presence of sulfuric acid and a catalyst, which is used as a complex catalyst, including sulfuric acid , sodium tungstate, sodium molybdate, after delignification, alkaline extraction of oxidized lignin is carried out at atmospheric pressure, followed by bleaching and alkaline refinement of cellulose, see RU Patent No. 2248421, IPC D21C 3/04 (2006.01), D21C3 / 22 (2006.01), 2005

The disadvantage of this method is the duration of the technological process and the low yield of the final product.

The technical problem is to reduce the time for obtaining highly refined cellulose and increase the yield of the target product.

The technical problem is solved by a method for producing highly refined cellulose, including delignification of crushed vegetable raw materials by cooking raw materials in a solution of hydrogen peroxide in the presence of sulfuric acid and a catalyst, which is used as a salt of molybdic acid, and bleaching, according to the invention, non-woody vegetable raw materials are taken as a vegetable raw material in the stages catalytic delignification and bleaching are carried out with continuous thermo-mechanochemical activation by passing the reaction mass of plant raw materials through the outer circuits of delignification and bleaching tanks equipped with an ultrasonic device or a device for rotating anisotropic ferromagnetic bodies for 60-90 minutes, while the delignification solution contains 0.6 wt ... %, hydrogen peroxide 2 wt. %. and catalyst sodium molybdate 0.2 wt. %, and bleaching is carried out after delignification in a peroxide-alkaline solution containing 6 wt. % sodium hydroxide and hydrogen peroxide with an initial concentration of 8 wt. % at a temperature of 90-95 ° C.

The preferred implementation of the method, when the thermomechanochemical activation of the delignification stage is carried out by passing the reaction mass of plant raw materials through the outer loop of the delignification vessel, equipped with more than one ultrasonic device, and the thermo-mechanochemical activation of the bleaching stage is carried out by passing the reaction mass through the outer loop of the bleaching vessel equipped with more than one device rotating anisotropic ferromagnetic bodies.

The solution of the technical problem makes it possible to obtain highly refined cellulose from non-woody plant raw materials with an α-cellulose content of up to 97.9%, with a residual lignin content of up to 0.25% and an increase in its yield to 50.5% in a shorter time.

The claimed method for producing highly refined cellulose differs from the prototype in that the reaction mass of plant raw materials at the stage of catalytic delignification and the reaction mass of plant raw materials at the bleaching stage are exposed to continuous thermo-mechanochemical activation by passing the reaction mass of plant raw materials through the outer contours of containers equipped with an ultrasonic device or a rotating anisotropic device. ferromagnetic bodies for 60-90 minutes.

The reaction mass in the outer circuits during the technological operations of delignification and bleaching can be exposed to force fields repeatedly. In this case, the delignification solution contains sulfuric acid 0.6 wt. %, hydrogen peroxide 2 wt. % and catalyst sodium molybdate 0.2 wt. %, and bleaching is carried out after delignification in a peroxide-alkaline solution containing 6 wt. % sodium hydroxide and hydrogen peroxide with an initial concentration of 8 wt. % at a temperature of 90-95 ° C.

As a plant material, it is possible to use any non-woody cellulose-containing material from annual plants, regardless of its nature: flax, rapeseed, hemp, alfalfa, amaranth, bagasse, rye straw, wheat, oats, etc.

The invention is illustrated by drawings, which depict: FIG. 1 general diagram of the delignification and bleaching tanks, where 1 is the plant raw material supply system, 2 is the delignification tank, 3 is the delignification tank agitator, 4 is the external contour of the delignification tank, 5 is the mass pump, 6 is the ultrasonic through-flow device, 7 is the pumping pipeline vegetable raw materials, 8 - washing filter, 9 - peroxide-alkaline bleaching tank, 10 - mixer, 11 - bleaching tank outer contour, 12 - mass pump, 13 - ultrasonic pass-through device.

FIG. 2 shows a diagram of the tanks for delignification and bleaching, where 1 is the plant feed system, 2 is the delignification tank, 3 is the mixer for the delignification tank, 4 is the outer loop of the delignification tank, 5 is the mass pump, 6a is a device with a flow of rotating anisotropic ferromagnetic bodies. placed in the inner cylindrical cavity connected to the inner cavity of the outer contour 4, 7 - the pipeline for pumping plant raw materials, 8 - washing filter, 9 - peroxide-alkaline bleaching tank, 10 - mixer, 11 - outer contour of the bleaching tank, 12 - mass -pump, 13a - a device with a flow of rotating anisotropic ferromagnetic bodies placed in the inner cylindrical cavity connected to the inner cavity of the outer contour 11. Anisotropic ferromagnetic bodies are driven into rotation by a source of electromagnetic fields placed on the outer surfaces of the device 6a and 13a;

Fig. 3 shows a diagram of the tanks for delignification and bleaching, where 1 is a plant feed system, 2 is a delignification tank, 3 is a delignification tank mixer, 4 is an external contour of a delignification tank, 5 is a mass pump, 6 is an ultrasonic device, 7 is pipeline for pumping plant raw materials, 8 - washing filter, 9 - peroxide-alkaline bleaching tank, 10 - stirrer, 11 - external circuit of the bleaching tank, 12 - mass pump, 13 - ultrasonic pass-through device, 6а and 13а - devices with rotating flow anisotropic ferromagnetic bodies.

The claimed method for obtaining highly refined cellulose is as follows:

Non-wood plant raw materials, which are taken as annual plant material, are crushed and the delignification process is carried out by cooking the raw material in a solution of hydrogen peroxide in the presence of sulfuric acid and a catalyst. The delignification solution contains sulfuric acid 0.6 wt. %, hydrogen peroxide 2 wt. % and catalyst sodium molybdate 0.2 wt. %, delignification temperature within 85-90 ° C, process time 60-90 minutes. Delignification of plant materials is carried out with continuous thermomechanochemical activation. From the delignification tank, the plant residue after washing is transferred to the peroxide-alkaline bleaching tank. The bleaching solution contains sodium hydroxide 6 wt. % and hydrogen peroxide 8 wt. %, bleaching temperature within 90-95 ° C, process time 60-90 minutes. The bleaching of plant materials is carried out with continuous thermo-mechanochemical activation. After bleaching, the resulting pulp is washed and dried at room temperature.

To compare the positive effect of the prototype and the claimed object, non-wood plant raw materials, such as rye, flax, are taken as plant raw materials for the prototype.

Example 1 according to the prototype, as a plant material take non-wood plant material rye.

To carry out acidic prehydrolysis, crushed plant material 8-15 mm long is fed into a prehydrolysis tank containing sulfuric acid with a concentration of 0.3 wt. %, heated to a temperature of 115 ° C and kept at this temperature for 2.5 hours. The plant residue is washed with water, transferred to a delignification vessel, and catalyzed peroxide delignification is carried out. The delignification solution contains hydrogen peroxide with an initial concentration of 17 wt. %, complex catalyst with a total concentration of 0.010 mol / dm ³ (including sulfuric acid 0.0034 mol / dm ³ (0.33 wt.%), sodium tungstate 0.0033 mol / dm ³ (0.1 wt.% ), sodium molybdate 0.0033 mol / dm ³ (0.097 wt.%)), delignification temperature in the range of 85-90 ° C, catalytic delignification time 150 minutes, stirring of the reaction mass is carried out with a stirrer 70 rpm. At the end of the delignification stage, the solid residue is washed and treated with a sodium hydroxide solution under the following conditions: NaOH concentration 4 wt. %, hydronic module 1: 4, temperature within 90-95 ° C, duration 150 minutes. The resulting pulp is then bleached by treatment with sodium hypochlorite solution at a temperature in the range of 20-25 ° C for 60 minutes and cold alkaline refining is carried out. Upgrading conditions: the concentration of the fibrous suspension is 5 wt. %, sodium hydroxide concentration 9 wt. %, temperature 15 ° C, process time 180 minutes. At the end of the refining process, the cellulose is washed with distilled water, dried in air at room temperature, and analyzed by standard methods.

Example 2 is similar to example 1.

The difference is that flax is taken as plant raw material.

Example 3 According to the claimed method, rye is taken as a non-woody plant material.

Shredded plant material 8-15 mm long is fed into a catalytic delignification tank 2, see FIG. 1. The delignification solution contains sulfuric acid 0.6 wt. %, hydrogen peroxide 2 wt. % and catalyst sodium molybdate (Na ₂ MoO ₄ ) 0.2 wt. %, delignification temperature 85-90 ° C, cooking time 90 minutes, stirring of the solution is carried out with a stirrer 3 at a speed of 70 per minute. At the stage of delignification, a solution of plant raw materials is pumped by an AEH-ZD 5 mass pump (capacity 3.4 m ³ / h) along the outer loop 4 of a delignification tank 2 with an inner diameter of a pipeline of 25 mm, in which flow-through ultrasonic devices "Hammer" 6 (capacity 3 m ³ / h, power 5.5 kW / h), the flow through the pipeline returns to the delignification tank. At the end of the delignification stage by mass pump 5 (AE.H-ZD-productivity 3.4 m ³ / h), the vegetable raw material is fed through the pipeline 7 to the washing filter 8, where it is washed, filtered, and fed to the bleaching tank 9. Bleaching solution contains 6 wt. % sodium hydroxide, hydrogen peroxide with an initial concentration of 8 wt. %. Mixing of the bleaching solution with the vegetable raw material is carried out with a mixer 10 at a speed of 70 per minute. Solution temperature in the range of 90-95 ° C, processing time 90 minutes. Simultaneously with peroxide-alkaline bleaching, thermo-mechanochemical activation of the reaction mass of plant raw materials is carried out. To do this, with a mass pump 12, a solution of the reaction mass of plant raw materials is passed through an ultrasonic device 13, which is located on the outer loop 11 of the bleaching tank 9.

At the end of the stage by the mass pump 12, an aqueous solution of plant raw materials is pumped at the stage of washing and drying. The quality of the resulting cellulose is analyzed by standard methods.

Example 4 is similar to example 3.

The difference is that the time of the technological stage of the plant raw material delignification is 60 minutes, the time of the technological stage of bleaching is 60 minutes.

Example 5 is similar to example 3.

The difference is that the stages of delignification and bleaching of plant materials, see FIG. 2, are carried out with continuous thermo-mechanochemical activation by pumping the reaction mass of plant materials with an AEH-ZD 5 mass pump along the outer loop 4 of the delignification tank 2 and the outer loop 11 of the bleaching tank 9, respectively, through devices with a flow of moving anisotropic ferromagnetic bodies 6a and 13a, driven by electromagnetic fields. Force action devices with ferromagnetic bodies with a diameter of 2 mm and a length of 15 mm with a diameter of the inner cavity of the device 70 mm and a length of 100 mm. Rotation speed of ferromagnetic bodies 3000 rpm

Example 6 is similar to example 5.

The difference is that the time of the technological stage of the plant raw material delignification is 60 minutes, the time of the technological stage of bleaching is 60 minutes.

Example 7 is similar to example 3.

The difference is that flax is taken as plant raw material.

Example 8 is similar to example 7.

The difference is that the time of the technological stage of the plant raw material delignification is 60 minutes, the time of the technological stage of bleaching is 60 minutes.

Example 9 is similar to example 7.

The difference is that continuous thermo-mechanochemical activation at the stage of delignification of plant raw materials, see Fig. 3, are carried out by pumping the reaction mass of plant raw materials through two ultrasonic devices 6 and 13, installed in series on the outer loop 4 of the delignification tank 2, and thermomechanochemical activation at the stage of bleaching of plant raw materials is carried out by pumping the reaction mass of plant raw materials through two devices with a stream of moving anisotropic ferromagnetic bodies 6a and 13a, installed in series on the outer contour 11 of the bleach tank 9.

Example 10 is similar to example 9.

The difference is that the time of the technological stage of the plant raw material delignification is 60 minutes, the time of the technological stage of bleaching is 60 minutes.

The indicators of cellulose obtained by the inventive method and prototype are shown in Table 1.

As can be seen from examples of specific implementation, the claimed method, in comparison with the prototype, allows you to obtain highly refined cellulose from non-woody plant materials with a content of α-cellulose up to 97.9%, with a residual lignin content up to 0.25% and increase its yield to 50.5% in a shorter time due to continuous thermomechanochemical activation of the reaction mass of plant raw materials at the stages of delignification and peroxide-alkaline bleaching.

Claims (2)

1. A method of obtaining highly refined cellulose, including the delignification of crushed vegetable raw materials by cooking raw materials in a solution of hydrogen peroxide in the presence of sulfuric acid and a catalyst, which are used as salts of molybdic acid, and bleaching, characterized in that non-woody vegetable raw materials are taken as vegetable raw materials, and the stages of catalytic delignification and bleaching are carried out with continuous thermo-mechanochemical activation by passing the reaction mass of plant raw materials through the outer contours of the delignification and bleaching tanks, equipped with an ultrasonic device or a device for rotating anisotropic ferromagnetic bodies for 60-90 minutes, while the delignification solution contains sulfuric acid 0, 6 wt. %., hydrogen peroxide 2 wt. %. and catalyst sodium molybdate 0.2 wt. %, and bleaching is carried out after delignification in a peroxide-alkaline solution containing 6 wt. % sodium hydroxide and hydrogen peroxide with an initial concentration of 8 wt. % at a temperature of 90-95 ° C. 2. The method according to claim 1, characterized in that the thermomechanochemical activation of delignification is carried out by passing the reaction mass of plant raw materials through the outer contour of the delignification vessel, equipped with more than one ultrasonic device, and the thermomechanochemical activation of the bleaching stage is carried out by passing the reaction mass through the outer contour of the bleaching vessel equipped with more than one rotating anisotropic ferromagnetic body.

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